why site is logged off me - eventhough session timout is not over?

[bixam.palsa]

hi everybody....

i need advice regarding statemanagement in asp.net 1.1

 presently my site is running with Session - but with this
 we are getting logged off unexpectedly while browsing.
 i am not able to understood why it is logging off - eventhough session timeout is not expired   

 I set Session.Timeout="180" - in the server they set it to 30 min ( will pgmatic timout override server side sessiontimeout or not )
 
 this is my code:

Login.aspx:
 Session.Contents("a")=TextBox1.Text
 Session.Timeout="180"

 Resp.Redi...........

 in the next page
 If (Session.Contents("a") = "") Then         
 Response.Redirect (" https://ssl106.alentus.com/pathwaystosuccess/PPEPM/Administrator/error_page.html")
 Else
       a = Session.Contents("a")
        Label1.Text = a
 End If

and i have alternates are QueryString Params only - bcz Hiddens won't work and Cookies we won't prefer.

if we use QueryString Params - we shold avoid showing Params on URL and Copy Paste shold not work.

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